Kenson River Restoration

In advance of the planning application for the proposed works, we will consult from 19 Februay until 19 March 2026. This will be an opportunity for you to have your say and shape the future of the restoration project.

Click to read the draft application documents and to provide your feedback

If you would like to see the plans in person and speak with our team, come along to our drop-in event in Llancarfan Village Hall (CF62 3AD) on Monday 2 March between 1pm and 6pm.

The aim of the project is to bring the river into ‘Good Ecological Status’ by restoring 2.5km of the river, and the re-meandering will result in an extension of up to 450m to the river channel.

Returning to the historical planform will restore natural geomorphological processes, such as the transportation and deposition of materials.

The 450m of increased river length will provide additional habitat for species such as critically endangered European eels, water voles and invertebrates. In turn this will contribute to a diverse and resilient habitat. The improvements in habitat quality and quantity will further support rewilding efforts underway at Fonmon Estate.

The increase in channel length and naturalised channel sinuosity will enhance habitat quality within this lower stretch of the river. While spawning opportunities here are mainly limited to species such as stickleback and bullhead, the improved channel form will support the upstream migration of fish, including eels, lamprey and trout, by providing increased cover and more varied habitat. These enhancements will offer wider ecological benefits beyond the project boundary and upstream towards the failing WFD Llancarfan waterbody, including improved conditions for juvenile fish such as eels.

The project will provide increased floodplain connectivity over 20 hectares. This means:

• Increased flood capacity within the valley.
• Slower water flow during flood events, with water spilling into the floodplain. This allows sediment to settle and infiltrate. The wetland habitat acts as a purifier, which improves water quality downstream.
• New ponds and meanders slowing water flow also act as refuge for species, which would otherwise be washed away by faster flowing water.

Upstream

A - Creation of berms made with brashy/woody material and willow spiling
B - Embankment removal and regraded banks
C - Riverbank planting with native species
D - Gravel/sediment introduction to create natural undulations in riverbed
E - Introduction of woody material/large wood
 

Downstream

A - Conservation Grazing
B - Embankment removal and regraded banks
C - Riverbank planting with native species
D - Improved connection to floodplain, reconnected historical channels and natural meanders

Detailed flood modelling of the River Kenson was carried out to understand how the area floods now and how it might change after the planned river restoration works.

The results show that the site floods in all scenarios - both before and after the restoration - which is what was expected (given that the site is an existing floodplain). 

Flooding is generally deepest in the southern part of the site and shallower in the north.

After the restoration, the modelling shows small but noticeable improvements in some places. Some areas outside the restored river corridor will see slightly less flooding, both in terms of flood depth and how far the water spreads. No areas outside of the scheme shall be adversely affected by an increase in flood risk.

Fluvial 1% AEP plus Climate Change Post-Development Grid Comparison

We tested the project using a major flood scenario often called a 1% Annual Exceedance Probability (AEP) or 1 in 100-year flood event. This means there is a 1% chance of such a flood happening in any given year. It does not mean it only happens once every 100 years.

In this large flood scenario, the modelling shows that the proposed restoration reduces the maximum water levels across the site and the surrounding floodplain when compared to the baseline levels:

• Up to 5 cm lower water levels in the north‑east area of the site (dark blue areas)
• Less than 1 cm reduction in the south‑west (green areas)

These small reductions occur because the river channel will be widened, allowing it to hold and move more water during high flows. This extra capacity creates modest but measurable local benefits compared with the current situation.

More detailed flood modelling results are included in the Pre-application consultation documents.

How is the project funded?
The project is funded by the Welsh Government Nature and Climate Emergency (NaCE) Capital Programme. The programme supports a number of environmental priorities including peatland restoration, metal mine remediation, fisheries, water quality and national forests.

What are the challenges or potential risks of the work?
The construction works and new features have the potential to impact trees in the river channel, however measures will be taken to limit and mitigate the impacts. Any disturbance to terrestrial and already established wetland habitats will be minimised through targeted species surveys, project oversight, mitigation and monitoring. In-channel disturbance during construction will be reduced using appropriate methods and timing.

Who are the project partners and stakeholders?
Natural Resources Wales and Fonmon Estate are working in partnership to progress the project. Other project stakeholders include Local Landowners & Tenant farmers, Tarmac, National Grid, Vale of Glamorgan Council, and Heneb. The design work is being completed by JBA Consulting, supported by a team of consultees as required.

When are the works scheduled to begin, and when is completion expected?
Construction is aiming to commence during the summer of 2026 with an estimated completion in autumn 2026, followed by a 5-year monitoring period.

What happens next?
A detailed design and supporting planning application is currently being prepared, with submission proposed in early 2026. A pre-application consultation event will take place ahead of formal submission, allowing for further questions and feedback, and to provide more detailed information on the proposals.

The first phase of improving the Kenson River WFD status was completed in summer 2025, by removing the failing weir at the south-west end of the river within the Fonmon Estate. The removal of this barrier will benefit wildlife at a local level and will also enable larger scale improvement opportunities in conjunction with the wider Kenson River restoration project.

The benefits of the weir are restoration of connectivity, benefiting biodiversity and water quality, as well as the removal of barriers to fish movement, and the restoration of natural river functions and sediment transfer. The removal will also reduce localised erosion and scour, as well as increasing the capacity of the channel during flood events and high tides.

Before weir removal

After weir removal